Going to extremes

Is it just coincidence, or is our changing climate staring us hotly in the face?

Just as record temperatures and bushfires turned the summer to cinders, many of the world's top climate scientists met in Australia.

That had to be coincidence.

Turned out though, that our 2012-13 summer gave an opportunity to underscore the known knowns of their science - and how we might better deal with extreme events.

An Intergovernmental Panel on Climate Change meeting in Hobart last week was bookended at the start by Tasmanian bushfires, and at the end by worsening Victorian and New South Wales fires - and Sydney's 45.8 degrees hottest day on record.

As he opened the meeting, Thomas Stocker, co-chair of IPCC Working Group I, pointed to the panel's special report on the risks of extreme events under climate change.

This indicated that what today was a one-in-20 year hottest day in Australia, might be six times more frequent within the next 30 to 40 years.

In the absence of curbed greenhouse emissions, such a day could be more than 10 times more frequent by the end of the 21st century.

The new normal could be the dull orange glow of a bushfire moon. And already the tremendous cost of these fires is being argued.

What to do?

First, rely on the scientific consensus. Reject the spurious merchants of doubt around the fringes of the climate debate.

Working Group I's report on the basic science of climate change will be finalised for release at the end of September. Meanwhile, we have the words of the last assessment to guide us.

''Warming is unequivocal,'' it says.

Next, don't expect certainty out of your scientists.

Peter Stott, of the UK Met. Office, who spoke at a crowded public lecture after the working group finished, underlined that it was not possible to to definitively link any single extreme event to climate change.

''But crucially, you can say how the odds have changed,'' Dr Stott said.

We should not expect every year to be warmer than the year before, he said. But we will see more records for warm years being broken, than records for cold years.

And third: it's the community, stupid.

US climatologist Linda Mearns, who also spoke at the lecture, looked to the reaction of her fellow New Yorkers to the destruction of Hurricane Sandy.

In fighting inundation they had no sure blueprint to work from.

''They began to develop plans knowing that they didn't know a lot, but that they will know more,'' Dr Mearns said.